robsmith9798

DTC code- P0113 IAT Sensor Circuit High Input.... i hooked computer diagnostic scanner up, the live data read; IAT temp -38 degrees(f) whether the engine was cold or warmed up. connected brand new IAT sensor and IAT temp still -38 degrees(f). checked harness side with multimeter and one of the inputs on the harness read 5v, the other input on the harness read nothing. Check engine light has been on for a month, erase it and it comes back. Dont kno how to fix this problem.....anybody?

2002_Z28_Six_Speed

iTrader: (19)

I am going to take a guess at this one.

The IAC shares a ground with the AC Pressure Sensor. Do you have that plugged in or is it bad??

Check out this diagram.

http://www.ls7power.com/diagrams/AC%...20Controls.gif

Check the C2-57 pin on the PCM and make sure it is getting continuity with the correct pin on the IAT sensor.

robsmith9798

i wouldnt kno what it looks like or where to find it or how to check it.....u gotta an actual picture?

Oskar_Z28

I got exactly same problem. The sensor has about 2k ohm resistance when cold. I have 5V going to the sensor with the engine on, but nothing on the purple wire going to the sensor. According to the schematic above, the purplr wire should be grounded through the PCM. When I checked continuity from the purple wire to the ground on a car, I had nothing. Today I will check the continuity between the purple wire and the PCM. I'll post up if I find something.

robsmith9798

thanks, let me kno when u find out. same thing but i dont kno how to test continuity on the ground/purple wire...all i kno is the pcm is sendin 5v >thru the tan wire (signal) >to the sensor (brand new sensor and works fine)......but the purple (ground) isnt sendin anything to the pcm .... probly y its causing it to read -38(f) (i think)........also too, i tried jumping the 2 connections (tan>purple...signal>ground) with a wire thinkin it would send 5v right back up the purple (ground) but still got no reading on IAT on the scan tool.... i was expecting the scan tool to read 242(f) or (whatever the max Temp(f) is). Correct me if im wrong but i assume: 0v > PCM = -38(f) ..and.. 5v > PCM = 242(f)? and any voltage in between 0v-5v would determine the IAT, depending on how much resistance there is thru the sensor caused by temp. changes? anyways i dont kno why a connection on the pcm should be bad, i dont kno what would cause this problem to happen, all i want to do is fix the f@#$er lol.... thanks

jimmyblue

iTrader: (11)

One side of the IAT should be about zero volts
from a PCM ground (PCM low reference). Take
the DMM (-) lead and find a good PCM ground
back by the PCM. Measure with the car running
of IGN on at least. Use a sewing needle to poke
into the wire near the IAT connector. One side
zero volts, the other side a volt or three, is what
you should see.

The fault says, the "volt or three" is more like the
5V pullup source. Should see this on the high side
wire. Question is, whether the low side wire is also
pulled up (ground fault in the harness) or the low
side -is- ground but the high side is 5V (IAT fault
inside, or connector fault). The other way to fail is
a harness open further up toward the PCM, in which
case both wires at the sensor will be about ground.

To summarize, measure both purple ground (PPL) and
tan sense (TAN) voltage at the sensor against a known
good PCM ground wire (either connector. Pin 1) and
see which of these fits:

PPL=0.0V TAN=1-3V : normal
PPL=0.0V TAN=5V : open circuit in sensor or connector
PPL=0.0V TAN=0.0V : open upstream of sensor (TAN)
PPL=5V TAN=5V : open ground (PPL)

Oskar_Z28

Here is what I found out today:

I had 5V in the tan wire and 0V in PPL. So I checked continuity between the connector and PCM harness point Red 57. I had no continuity. So I poked the PPL wire near the PCM harness with a needle and checked continuity between PCM connector and PPL wire. Everything was good. Then I repeated the same thing on the sensor end and found that the connector was bad. As I was checking it, the wire actually fell out of the connector. So I checked continuty to the PCM and it was good.

Question: Where can I buy a connector like that?

I might end up rigging something for now if I have to go to a dealer to but that.

Jimmy, thanks for the info. I followed your procedure along with a diagram.

I'll post up once I get it fixed.

I hate electrical circuits. I am a mechanical guy. !!!!

robsmith9798

same here 0v on purple wire, still 5v on tan wire, brand new sensor, car in mint condition/bonestock almost.....and when i did the free ram air mod i had to wrestle the iat connector off, i possibly coulda losen the wire in the connector....im gonna do the process u explained n ill get back the info when im finished, thanks

jimmyblue

iTrader: (11)

If the wire came out with its pin attached you can
probably just re-bend the little stop-tang on it and
snap it back in.

If the wire came out, I'd poke out the pin (may need
a needle or wire hook to disengage said stop-tang
from its catch) and solder the wire on.

Casper's --> sells IAT pigtails if the connector / pins
are too messed up to be worth the hassle.

robsmith9798

hey jimmy, what is an open circuit? how do u test for it? how do u fix it? im readin 0v ppl and 5v tan. what do u recommend?

jimmyblue

iTrader: (11)

Open means no current path, infinite resistance.
It appears that the IAT itself, or the connector,
has a problem.

Try pulling it off the IAT and put a 1K-ohm Radio
Shack resistor into the IAT connector terminals.
You should see an IAT reading of about 120F
and the voltage between purple and tan should
be a volt or two.

Get an ohmmeter (DMM) and measure the resistance
of the IAT sensor. At room temp (70F) it ought to
be 467 ohms. Call anything in the 300-500 range,
close enough if you don't know the temp.

If both of these work out as described then it has
to be something about the connector, like a loose
pin that maybe gets intermittent contact.

robsmith9798

i bought a brand new factory sensor and tested it...it works fine...the reading is always between 300-500 inside the house and it changes when i put a hair dryer up to it also when i blow cold air on it.....so IAT sensor good

now with the connector/harness test....i dont fully understand exactly what to do.
do i test/connect the harness/connector with the 1k-ohm resistor? or do i test/connect the pcm IAT terminals with the 1k-ohm resistor? i didnt understand if i was testing the connector/harness..or the actual pcm IAT function/system itself...

also too if u could...could u explain how the IAT circuit works? im confused on why the tan wire should put out 1-3v, and why it would put out 5v with an open circuit....

anyways thanks again, ill try to test it as best as i can

robsmith9798

found the problem, purple wire was loose n came out of connector

bluezq8

iTrader: (6)

Sorry to dig up a really old thread, but I have this exact question and I can't find an answer anywhere. I see 1-3V when i measure the voltage on the sensor, but my temps read ~20-25* higher than they should.
Can this temperature offset be adjusted in the tune?